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How do I tell what frequency my ported box is tuned to

 

New member
Username: Jb502

Omaha, NE

Post Number: 4
Registered: Jun-05
I have a ported box with two brand new 12" alpine type r's. I don't know what the box is ported to. I have a feeling it is ported too high though because it just doesn't hit that low. I can't feel it in my gut like i want to be able too. Is this a sign of the box being ported to high. If so how do i fix it, shorted port or longer. Thanks in advance
 

Gold Member
Username: Insearchofbass

Post Number: 3165
Registered: Jun-04
to port lower you need more port length
 

New member
Username: Jb502

Omaha, NE

Post Number: 7
Registered: Jun-05
ok sean hopefully you see this, you seem to be pretty knowledeable. I am going to give you my box dimension, tell me what you think.
Length=30 inches
Depth=24 1/4 inches
Tall-=12 inches

those are the inside measurements making the box 5.05 cubic feet. The port is an L shaped port that starts on one side of the box and goes all the way to the back, making that part 24 1/4 inches, then it turns on the inside of the box for 19 inches. It is roughly 38-44 inches long (not sure about the correct way to add up the length where it makes the turn). The port is 12 inches tall, and 5 1/5 inches wide in the inside. That makes it a volume of 1.45-1.7. What do you think, should i have a custom box make or should this one do. It just doesn't hit low enough. Do you think i need a bigger amp. I have an alpine mrd-m605 that puts out 600 rms. The subs will handle more. The place I bought it will let me upgrade to the mrd-m1005 that puts our 1000 watts rms. What would you do. thanks for any help i get.
 

Gold Member
Username: Insearchofbass

Post Number: 3188
Registered: Jun-04
if its 38 long port wise its tuned to 38 hz taking off the 1.70 cf you estimated off the box volume if its 44 long you port is tuned about 31 hz but you said you didnt know how to add for the bends so im assuming you didnt add them into the port length and that would add half the port width for every turn so in your case another 2.25 extra for each one you have so im assuming two bends that would put you at a 30 hz tune at 44 inches and 32 hz at 38 inches accounting for the bends
 

Gold Member
Username: Insearchofbass

Post Number: 3189
Registered: Jun-04
opps i was off a little but close enough i did 5 inches extra not 4.5
 

New member
Username: Jb502

Omaha, NE

Post Number: 8
Registered: Jun-05
thanks for the quick response. So i guess it isn't tuned to high like i though. I wonder why it doesn't seem like it hits that low. The box seems to be about the perfect size and tuned just right. Any ideas.
 

Gold Member
Username: Insearchofbass

Post Number: 3194
Registered: Jun-04
what subs are they and what amp do you have on them
 

New member
Username: Jb502

Omaha, NE

Post Number: 9
Registered: Jun-05
Brand New Alpine Type r's, with the alpine mrd-m605, and an alpine cda-9855
 

New member
Username: Jb502

Omaha, NE

Post Number: 10
Registered: Jun-05
I have
2-brand new alpine type r's, 12 inch
mrd-m605 amp
cda-9855 head unit
 

Gold Member
Username: Insearchofbass

Post Number: 3195
Registered: Jun-04
check your subsonic filter settings and set it to about 30 hz and then check your subwoofer level adjustment they start in negative 15 and go to zero so dont be afraid to use it. The apline cd player also has a subwoofer adjustment your want to set. Tinker with those settings a bit and let me know if there is any improvement.
 

Bronze Member
Username: Jb502

Omaha, NE

Post Number: 11
Registered: Jun-05
i have had my subsonic set at thirty since i got it, and the bass boost on the amp all the way up, and the one on the cd player all the way up as well. I can turn it up and it gets pretty loud, but it starts to distort, which I don't understand because i am underpowering the subs. Is it my amp clipping that is causing the noise from my subs. it seems like they could go louder, but then they start to make noise. I am not sure if I am clipping the amp. That is why i think I may need to go with the mrd-m1005, what do you think?
 

Gold Member
Username: Insearchofbass

Post Number: 3208
Registered: Jun-04
they are clipping yes you dont want all of it all the way up and adding that amp will only increase your db by like 2 db anyway ....get your stuff set up by a professional with equipment it will make a definate diffrence...if you want more spl after that theres other cheaper ways to do that
 

Bronze Member
Username: Big_oso

Post Number: 38
Registered: Jun-05
what are cheaper ways cuz im going to be running the same setup basically well the two alpine r's 12" and a 1000 watt class d interfire
 

Bronze Member
Username: Jb502

Omaha, NE

Post Number: 14
Registered: Jun-05
cheaper ways for what
 

Bronze Member
Username: Jb502

Omaha, NE

Post Number: 15
Registered: Jun-05
sean, i am getting it set up by a pro at stereo west. I am getting the mrd-m1005, and having a custom ported box built with the subs firing down in my 200 ford f-250. I hope this makes a difference. But what are some cheaper ways to get more spl. Oh, i also just order a bulk pack of dynamat extreme, you ever used it?
 

Gold Member
Username: Insearchofbass

Post Number: 3213
Registered: Jun-04
No i havent used dynamat but im sure it will be a wise investment. Some cheaper ways are the dynamat you purchased. A line driver to increase your line out voltage (Phoenix gold line driver 8 volts if the amp can take it) Alpine decks are weak in that area contrary to their claimed 4 volts out. You could also place a reflector board inside your box to excite the air this trick can add as much as 3 db. One other trick you can do is a phoenix gold bass cube.
 

Bronze Member
Username: Jb502

Omaha, NE

Post Number: 16
Registered: Jun-05
yes i have heard of the bass cube. what exactly is a reflector board though i would love to tell the guy that boilds my box to put one in. He is a professtional at stereowest so he should know. not very familiar with a line driver either. what does increasing my output voltage do for me. the will take up to 8 volts.
 

Gold Member
Username: Insearchofbass

Post Number: 3216
Registered: Jun-04
Heres the link to the reflector board idea ...he calls it a baffled box. A line driver will clean up you output signal to your amplfier requiring less turn of the knob for the same output and in my opinion increasing not only the sound quality but the spl as a result. If your amp can take a 8 volt signal that would be a major step up from alpines true output of somewhere around 2 volts.

http://www.sounddomain.com/ride/318757/4
 

Silver Member
Username: Rzarector

Coquitlam, Bc Canada

Post Number: 428
Registered: Dec-04
box is a lil to big to .. should be kept between .75 - 1.75 cu ft per sub
 

Bronze Member
Username: Jb502

Omaha, NE

Post Number: 19
Registered: Jun-05
so basically just run a board behind my subs about 5/8ths of the way across the box
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